I hope nobody supposes it's called an "ethical operating plan" just because the Co-operative Group's PR team liked the sound of the resulting acronym – "the Co-op's Eop". That would be to miss the point. It's an Eop because ethics and social justice lie at the very heart of this new sustainability initiative.

The sustainability world has always been somewhat ambivalent about social justice. For some (including myself) it is as central to the notion of sustainable development as living within environmental limits. The two have to march hand in hand, and if they don't what emerges will never be sustainable anyway.

For others, it's obviously important, but it's not central, let alone a precondition of what sustainable development is all about.

Without a shadow of a doubt, the Co-op is the most explicit of all the big UK corporates about the centrality of social justice. While other progressive companies may eloquently bemoan the lack of social justice in a society such as ours, they argue persuasively that it's just not their responsibility. Redistributing wealth and sorting out injustice is the job of governments, not business.

They are absolutely right, up to a point. And that point is where a board of directors' fiduciary duty to protect the interests of its shareholders has to trump wider concerns about the state of the economy.

The Co-op isn't like that. It's owned (and democratically controlled) by its members, all 6 million of them. That gives it the privilege of putting social justice at the heart of its strategy, with or without a business case. While others have to keep their shareholders sweet by demonstrating that all their sustainability endeavours will benefit them – either directly or indirectly, in the long run if not immediately – the Co-op just has to keep its members sweet by doing what they've mandated it to do anyway. As Peter Marks, Co-op's chief executive, says, "The plc model is not the only corporate game in town".

But that's the real differentiator with the Co-op. On the burgeoning raft of issues that now make up the sustainability agenda for the Co-op and its competitors (in each of its different sectors), it will jostle for position in the various league tables assessing who has done better than whom. Win some, lose some – though rarely by much, in the Co-op's case.

But no one else is out there loudly banging the social justice drum, committing profits explicitly to tackling both poverty here in the UK (£5m) and global poverty (another £7m). No one else is actively campaigning for a more "balanced and sustainable economy" or vociferously lobbying, for instance, for an end to some of the absurd investments that exacerbate the problem of accelerating climate change (such as the Tar Sands in Alberta), while simultaneously setting out to be the best in terms of reducing its own operational CO₂ emissions and to increase its commercial lending in the area of energy efficiency and renewables – from £400m today to around £1bn. That's properly joined-up climate leadership.

And how David Cameron must wish that he could have a great big slice of the Co-op's very own big society pie. If they weren't so ideologically hamstrung, Tory advocates of its "big society" initiative would recognise the massive contribution that the co-operative movement has always made to delivering real social value as well as thriving businesses – let alone the role that co-operation can play in a more sustainable future.

While ministers carry on talking, the Co-op will just get on with it – supporting new Cooperative schools, setting up an international Co-operative Development Loan Fund, getting involved in more than 10,000 community initiatives every year, particularly around stores and branches, creating 2000 new apprenticeships through its Co-operative academy, supporting more and more young people through its Co-operative Enterprise Hub, proactively addressing the problems of financial exclusion and the lack of financial literacy among young people.

These are just a few of the reasons why it's now aiming to increase membership from 6 million today to 20 million by 2020 – at the rate of more than a million a year.

All good stuff. Hence my few words of encouragement in the Co-op's press release: "By launching this ethical operating plan, the Co-operative is taking corporate sustainability into a new era. Other businesses will now be seeking to benchmark themselves against this plan".Jonathon Porritt is a founder director of Forum for the Future